Articles
PREPLANT SEED TREATMENT OF TOMATO FOR CONTROL OF XANTHOMONAS CAMPESTRIS (PAMM.) DOWS. PV. VESICATORIA (DOIDGE) DYE
Pathogen-free seed is essential to seedling production houses and the field tomato grower.
Seed treatment studies were conducted in vitro and in vivo from 1980 to 1984 at Tropical Research and Education Center, Homestead.
For the in vitro studies Form-A-Turf at 1:250, Formalin at 1:250, NaOCI at 1:4 and hot water at 56°C for 30 min provided 100 percent pathogen-free seed.
None of the treatments reduced seed germination.
In in vivo studies percent pathogen-free seed, and seed-germination reduction, varied according to adequacy of grower facilities for adequate hot-water temperature control and flushing of applied NaOCl from the seed.
Bacterial spot of tomato caused by Xanthomonas campestris (Pamm.) Dows. pv. vesicatoria (Doidge) Dye is a serious foliar and fruit disease of tomato (Conover, 1954, Goode and Sasser, 1980, McMillan, 1980, McMillan et al., 1972, Stall and Thayer, 1962). Foliar sprays of maneb, mancozeb, streptomycin and copper are the chemicals which the tomato grower has to protect his crop once the disease is evident.
Streptomycin was very effective in controlling bacterial spot in the early 1950’s (Conover, 1954) but by 1962 it had lost its effectiveness due to development in resistance in the X. c. vesicatoria population in the U.S. (Stakman and Harrar, 1957). This historical event left only maneb, mancozeb and copper which are not very effective when disease pressure is high.
A point of contention in Florida has always been what is the source of inoculum.
Is it infested plant residue, weed host, volunteers or contaminated seeds? In old tomato production fields all four of above sources for the bacteria are possible but only contaminated seeds could be responsible for disease in isolated virgin fields.
Seeds contaminated with fungi and bacteria have plagued man from the beginning (Stakman and Harrar, 1957). Various seed treatment chemicals such as formalin, calcium and sodium hypochlorite, have been used as seed disinfectants dating back to 1915 and before (Stakman and Harrar, 1952, Wilson, 1915). Early interest in sodium hypochlorite seed treatment was very low because of seed germination reduction (Abdul-Baki, 1974, Dempsey and Walker, 1973, McCollum and Linn, 1955, Mikkelsen and Sinah, 1961). However, more recent studies have found that proper treatment caused no reduction or only minimal in germination in tomatoes and peppers (Dempsey and Walker, 1973, McCollum and Linn, 1955) and actually stimulated germination of pepper and rice (Fieldhouse and Sasser, 1975, McMillan et al., 1972).